1. Field of the Invention
The present invention relates to non-refluxing suction canister systems and components therefor, and more specifically to such systems having canisters dosed by anti-refluxing valves or which have flexible liners.
2. Related Art
During operative surgery and other medical and biological procedures, suction canister systems are used to collect fluids from a patient, including blood, saline, and any other fluids which may accumulate or must be removed and contained during the procedure and disposed of after the procedure. The collection system uses suction canisters and a vacuum source. While a single canister can be and is often used, a multiple canister suction system will be described because the use and operation of a single canister system is apparent from that for a multiple system. Multiple canisters are arranged in tandem with a first canister having a suction tube to collect fluids from a source and to deposit the fluids in the first canister. Downstream canisters are coupled together with their vacuum sources applied in series or in parallel from a vacuum source connected at the end canister.
Typically, a canister unit includes an open-top cylindrical canister closed by a cover or lid to which is sealed an internal liner to be contained in the canister. Vacuum is applied through the canister wall to the space or cavity between the liner and the canister wall to expand the liner outwardly toward the canister wall. Vacuum is also applied for each canister to a vacuum port in the lid to develop a subatmospheric pressure or vacuum within the liner, which vacuum then also develops at the collection tube at the desired level. Tandem tubes connect the interior of the liner of the first canister to the inlet port on the lid of the next succeeding canister so that when the first canister fills, fluid in the first canister thereafter passes to the second canister, and so on.
The lid typically includes several access ports with associated attachment or connection elements. A vacuum port accepts a tube from the vacuum source to apply vacuum internal to the liner. An inlet or patient port accepts one end of the suction tube. A large access port is typically capped until a fluid setting agent such as Isolizer is to be added. An outlet or "ortho" port includes a wider riser portion than the patient port for connection of a suction tube during orthopaedic operations or for connection of a tandem tube for connecting an additional collection canister to the first. The vacuum port of each canister includes a float valve to prevent withdrawal of fluids into the vacuum system. However, the other ports in the lid which are exposed to the fluids lack any valve and are subject to reflux and may lead to contamination of personnel or a working area.
In situations where one or more canisters become filled before the end of the procedure, fluid may reflux or come out of one or more ports under certain circumstances. For example, if vacuum is removed from the system, the pressure differential between atmosphere on the one hand and the cavity between the canister and the lining on the other, created by the vacuum between the canister and the liner, is removed. Removal of the vacuum allows the liner to collapse somewhat, due to liner elasticity, increasing the internal pressure on the fluid inside the liner. This increased pressure could cause fluid to be pushed out through the suction tube toward the patient or otherwise out the collection tube. Fluid may also be pushed out the port for the tandem tube toward a secondary canister. When the interconnected canisters are disconnected, fluid may be ejected from the tandem tube, thereby possibly contaminating surfaces or personnel.
As a further result of the increased liner pressure differential, the canister liner may still be sufficiently enlarged or inflated to remain in contact with the walls of the canister. To remove the lid and liner, personnel often try to manipulate the lid and liner either by grasping the liner or grasping fittings on the lid to gain an advantage in forcibly removing the lid and liner from the canister. Such manipulation often puts pressure on the liner thereby increasing the tendency of the liner to eject fluid, and also places force on the fittings which could cause removal of caps on fittings or breakage of fittings, connections or caps. Each of these could cause contamination through ejection of fluids.
As long as vacuum is applied to the system, steady state exists throughout the system. However, once vacuum is removed or once vacuum is removed and personnel attempt to dismantle the system to dispose of the filled liners, the possibility of contamination increases. There exists, therefore, a need for a system which further minimizes the possibility of loss of fluid or contamination in vacuum collection systems.